As the desire for enhanced communication bandwidth escalates, transmission media need to convey information at higher speeds while maintaining signal fidelity. However, effects such as noise, interference, crosstalk, alien crosstalk, and/or alien equal-level far-end crosstalk (“ELFEXT”) can strengthen with increased data rates, thereby degrading signal quality or integrity. For example, when two cables are disposed adjacent one another, data transmission in one cable can induce signal problems in the other cable via alien crosstalk interference.
Additionally, in certain types of cables, it is desirable to separate internal cable components. For example, certain cables make use of multiple twisted pairs of conductors to communicate signals. In each pair, the wires are twisted together in a helical fashion to form a balanced transmission line. When twisted pairs are placed in close proximity, such as within the core of a cable, electrical energy may be transferred from one pair of the cable to another pair. This crosstalk causes interference to the information being transmitted through the twisted pairs and can reduce the data transmission rate and cause an increase in bit rate error. Interlinking typically occurs when two adjacent twisted pairs are pressed together, and interlinking can lead to an increase in crosstalk among the wires of adjacent twisted pairs.
One approach to addressing signal degradation associated with communication cables is to circumferentially encase cables or various cable components in a continuous shield, such as a flexible metallic tube or a foil that coaxially surrounds the cable's conductors. However, shielding based on conventional technology can be expensive to manufacture and/or cumbersome to install in the field. In particular, complications can arise when a cable is encased by a shield that is electrically continuous between the two ends of the cable. The continuous shield can inadvertently carry voltage along the cable, for example from one terminal device at one end of the cable towards another terminal device at the other end of the cable. If a person contacts the shielding, the person may receive a shock if the shielding is not properly grounded. Accordingly, continuous cable shields are typically required to be grounded at both ends of the cable to reduce shock hazards and loop currents that can interfere with transmitted signals. Such a continuous shield can also set up standing waves of electromagnetic energy based on signals received from nearby energy sources. In this scenario, the shield's standing wave can radiate electromagnetic energy, somewhat like an antenna, that may interfere with wireless communication devices or other sensitive equipment operating nearby.
In order to address the limitations of continuous shields, segmented or discontinuous shields have been incorporated into certain cables. These segmented shields typically include metallic patches formed on a polymeric film with gaps or spaces formed between adjacent patches to maintain electrical discontinuity. Thus, the metallic patches function as an electromagnetic shield; however, it is not necessary to ground the shields during cable installation. Current segmented shield designs are typically manufactured by wrapping a shield tape either longitudinally or helically around a cable core or desired cable components. However, the spaces or gaps between the metallic patches may lead to electrical perturbations and decreased performance in the cable. Additionally, when a shield is wrapped around cable components, a space or gap may exist at an overlap region in which one edge of the shield overlaps the other edge in a circumferential direction. Accordingly, there is an opportunity for improved segmented shields, methods or techniques for forming segmented shields, and/or cables incorporating segmented shields.
Additionally, in order to improve crosstalk performance, separators (also referred to as separation fillers, fillers, interior supports, or splines) have been inserted into many conventional cables. These separators serve to separate adjacent twisted pairs and limit or prevent interlinking of the twisted pairs. Certain separators incorporate metallic material that performs a shielding function. However, these conventional separators typically suffer from the same problems as those described above for conventional shields. More specifically, separators having continuous metallic material can lead to shocking hazards unless properly grounded. Additionally, separators including discontinuous metallic material include gaps or spaces between metallic patches that may lead to electrical perturbations and decreased cable performance. Accordingly, there is an opportunity for improved separators or separation fillers for use in cables. There is additionally an opportunity for improved separators or separation fillers that include discontinuous patches or sections of shielding material, as well as cables incorporating such separators.